Thursday, October 29, 2015

eVox verses eVelo electric bicycles


This is the first electric bicycle that I’ve seen that has a good drive system. Most e-bikes waste too much power just getting up to speed, because they are in the wrong gear. Especially hub motors; the only way to lower the very high gear that hub motors are set at, is by lacing them into a smaller wheel.

It may not be geared right for hill climbing with cargo on our steep hills. But when you consider that brushless motors are able to produce much more power than is posted on the label, you can see why this e-bike has so much potential. This is the way the Elf car can climb steep hills with only a 750 watt motor.

I don't think they want people to see how small their motor is.
Another good argument for custom made e-Bikes.

The motor uses high voltage for high speed so that it can be a smaller size. They chose a micro-V belt to help keep a hard acceleration from destroying the spokes. And because routing most of the power through a belt will make your drive chain last much longer.

To keep the battery size small, the eVox cruises at about 500 watts, up to 20mph on flat land (more if you pedal). But when you need more power, you can climb steeper hills with as much as 750 watts for up to five minutes without frying the motor and controller; longer than most e-bikes simply because they use a high voltage motor.

The majority of the heat that can damage the motor and controller comes from the amps of current. By choosing a system that has higher volts, you can achieve the same amount of power with fewer amps.

The display panel will actually show you real-time wattage draw from the battery; this is not available on all e-bikes.

Most humans can't produce more power than  about 186watts, bicycle drive chains were made for a little more power but not 750watts.

This e-bike could use a lower gear to move 400lbs up an 8% grade. With 750 watts a 12mph gear is needed; if lower gears are available they do not want to tell me exactly how much lower; after all that would require calculations.

If you have strong enough legs you could add 250w for a 1000w hill climb. That is enough power to climb a 6% grade with 400lbs at close to 17mph, or a 5% grade at just under 20mph. Or 350 lbs up a 6% grade at about 18-19mph assuming the powered side is in the right gear. But Remember I am talking about total combined weight.

If you have an 8% grade your going to slow down to about 10mph or less with the gear set as high as it comes from the factory (I do not know exactly what the power drop is when the gear is not set right). Too bad they don’t just do a graph of what it can actually do with at least 350lbs.

Unfortunately this does not use a disc brake. It is very difficult to fit a disc brake with a belt drive.

So until enough people complain about it not being strong enough you will have to build your own motorized cargo bike. Hauling cargo on a bicycle will become essential very soon.

Mass produced electric cycles are made for generic flat terrain. But this is good for people that know what it takes to climb hills with cargo. There needs to be at least one person in every town with steep hills, turning people’s cycle trucks into powerful hill climbers.

Don’t be suckered into buying a big over powered mid drive, you don’t need it. Read more about why this kind of gearing is so good:

Ask them what amps the controller is set for:

A 500 watt electric bicycle conversion kit may be listed as a 500 watt kit, yet a closer inspection could show that the kit comes with a 48V battery and a 20 amp peak controller. The math shows us that this kit is in fact capable of putting out 48V x 20A=960 watts, essentially a 1,000 watt kit.


 The only thing that e-Velo has going for it, other than disc brakes, suspension and lower price, is the worm gear that allows for a larger motor 600 watts.  (their 500watt motor actually draws 720 watts maximum, But what is the actual output at the drive wheel?). 

All the power goes through the bicycle drive chain. It will wear out faster and there is the possibility of it snapping. Bicycle drive chains were made for human power, less than one-third HP!       

This bicycle would be much better if it had a belt drive on the left side.        

1 comment:

Unknown said...

Interesting and important information. It is really beneficial for us. Thanks